The parent invention of the noted ""819 application relates to crankcase ventilation filters for diesel engines.
Diesel engines have crankcase vents to relieve pressure buildup in the engine. A frequent cause of pressure buildup in the engine is from air leaking past the piston rings into the crankcase. The air that is vented out of the crankcase, also known as blow-by gas or crankcase gas, contains soot and oil mist particles. For many years, the blow-by gas along with the oil and soot was vented to atmosphere through a xe2x80x9croad tubexe2x80x9d to direct the flow to a desired area such as the ground, or away from specific engine parts. In recent years, metal mesh filters have been used to try and remove some of the larger oil droplets from the blow-by stream. These have had mixed results in the field. There have also been after market products which remove oil mist and soot from engine blow-by gas. These products have been designed for industrial and stationary applications, and are usually too large and bulky for mobile applications.
Over the past few years, for appearance and environmental reasons, there has been motivation to eliminate the xe2x80x9croad tubexe2x80x9d type of design, and close the crankcase ventilation system. Closing the crankcase ventilation system means returning the blow-by gas back to the incoming combustion air stream to the engine, for example at the air cleaner or turbocharger. If a closed crankcase system is desired, aerosol sized droplets and mists, which for the most part are ignored in an open system, should be removed. This is desired in a closed system in order to avoid adverse effects on various engine components, especially the turbocharger and after cooler. To do this, a degree of filtration beyond metal mesh is desired.
Packaging a closed crankcase ventilation system in a diesel engine compartment is a problem because of limited space. A closed crankcase ventilation, CCV, system requires routing hoses from the crankcase vent on the engine to the CCV housing, and from the CCV housing to either the dirty side of the air filter or to the turbo inlet of the diesel engine. Furthermore, a drain line needs to be run from the CCV housing back to the oil sump. A xe2x80x9cstand alonexe2x80x9d CCV system will have certain envelope requirements. For example, in a mid-range diesel engine, e.g. 150 to 300 horsepower, a projected envelope size would be a cylindrical housing of about four inches outer diameter and six to seven inches long plus room for connecting hoses, drain lines and valves. In mobile diesel engine applications, finding this amount of space in a convenient location is a problem.
The parent invention provides a diesel engine crankcase ventilation filter addressing and solving the above noted packaging and space problem. The parent invention provides a flat low profile crankcase ventilation filter. In preferred form, the parent invention enables mounting of the flat low profile filter housing directly on the diesel engine valve cover, with minimum space requirements and minimum plumbing requirements.
The present invention arose during continuing development efforts relating to the parent invention of the noted ""819 application. The present invention provides various improvements, refinements, and further embodiments.
In the preferred form of the present invention, a closed crankcase ventilation system is provided on top of the valve cover of a diesel engine. Gases including oil and air are brought into a series of chambers with the initial chambers devoted to inertial separation and the final chambers devoted to separation by flowing through a fibrous media. The valve cover serves as the bottom piece of the system, while the top part of the system is defined by a second cover independent of the valve cover. The filter seals between the valve cover and the second cover. An engine valve cover is provided with multiple chambers integrally formed into the top surface of the valve cover. A CDR, crankcase depression regulation, valve receives blow-by gases from the engine and discharges the gases into the first chamber in the valve cover. A filter element receives partially cleaned gases from the first series of chambers and discharges the cleaned gases to an outlet region. A second top cover forms the top portion of the chambers and seals the system. Air and crankcase gases containing oil mist and other contaminants exit the engine and are routed into the CDR valve through a hose or other similar device. The purpose of the CDR valve is to prevent excessive negative pressure in the engine chamber by restricting flow when vacuum in the engine reaches a certain level. The valve uses a spring and diaphragm to achieve this pressure regulation. Attached to the outlet of the CDR valve is one or more accelerator nozzles that accelerate the flow coming out of the CDR valve as it enters the first separation chamber of the valve cover. The gases out of this nozzle are directed toward an inertial separation region system. The intent of directing the gas flow into the inertial separation region is to remove course droplets and mist particles from the air stream. Each chamber may have a separate drain. The gas flow is then directed into a plenum which is defined by the second cover and the top surface of the element. This gas then flows downwardly through a coalescing element into a bottom plenum defined by the top of the valve cover and the bottom surface of the element. The coalescing element is a final stage of contaminant removal. In the bottom plenum, there are separate outlets for the air flow and the coalesced oil. The valve cover has flow channels leading to a sump in the cover, which helps separate the liquid flow from the gaseous flow. The liquid flow is drained back to the oil sump of the engine. The air flow is vented out of the bottom plenum and routed back into the engine, either into the intake upstream of the turbocharger or another location in the air intake stream of the engine.